Observing the birth of a planet

Public Release: 1-Jul-2015
Observing the birth of a planet

ETH Zurich
This news release is available in German.

Observing time at the European Southern Observatory (ESO) on Paranal Mountain is a very precious commodity - and yet the Very Large Telescope (VLT) in Chile spent an entire night with a high-resolution infrared camera pointed at a single object in the night sky. The data collected by the Naco optics instrument enabled an international team headed by ETH Zurich's Sascha Quanz to confirm its earlier hypothesis: that a young gas planet - presumed not unlike Jupiter in our own solar system - is orbiting the star designated HD 100546.

At "just" 335 light years away, HD 100546 is one of our near cosmic neighbours, and its age of five to ten million years makes it relatively young in astronomical terms. Like many young stars, it is surrounded by a massive disk of gas and dust. The outer reaches of this disk are home to the protoplanet, which lies at a distance from its parent star that is some fifty times greater than the distance between the Earth and the Sun.

Flung to the outskirts - an unlikely scenario

The team first postulated the existence of this young planet in an initial research paper published back in 2013. At the time, however, the researchers were still debating another possible explanation for the data they had collected, namely that the observed object might be a more massive - albeit older - giant planet that had formed further inside the circumstellar disk before being hurled outward. "It's a scenario we still can't rule out completely," Quanz admits. "But it's much less likely than our explanation, which suggests that what we're seeing is the birth of a planet."

If the object were an older planet that had formed earlier and closer to the star, its ejection trajectory would have to meet certain conditions for the researchers to be able to observe it now: It would have to be ejected directly in the plane of the gas and dust disk and at precisely the right time. "That would be a pretty huge coincidence," says Quanz. This is why the team prefers the more natural interpretation, which at any rate is unusual enough. In addition, their latest observations have convinced the researchers that the signal they are picking up cannot be coming from a background source. "The best explanation for the observed phenomena is that a new planet is actually in the process of formation, embedded in the disk surrounding its parent star" - that was the conclusion of the study, which is published in the Astrophysical Journal. The study was conducted within the framework of "PlanetS", one of Switzerland's National Centres of Competence in Research.

More:
http://www.eurekalert.org/pub_releases/2015-07/ez-otb070115.php

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Is This a Baby Picture of a Giant Planet?
Feb 28, 2013 03:22 PM ET // by Jason Major
http://news.discovery.com/space/alien-life-exoplanets/is-this-a-baby-picture-of-a-giant-planet-130228.htm











European Southern Observatory
Paranal Chile [/center]